The Democratic senator from California, known for sharp questioning on Capitol Hill, joins a growing field of candidates fighting for the nomination of a party that is increasingly non-white and fueled by women.

The Rev. Martin Luther King Jr. was autographing books at a department store in 1958 when a woman attacked him with a letter opener, which became lodged near his aorta. The civil-rights icon described the stabbing in his famous “Mountaintop” sermon a decade later, the night before his assassination.

Democratic presidential aspirants fanned out across the country to praise the legacy of the Rev. Martin Luther King Jr. and offer direct appeals to black voters who will play a major role in choosing a 2020 nominee. Meanwhile, President Trump and Vice President Pence briefly visited the King memorial in D.C.

An incident at the Lincoln Memorial that involved indigenous rights activists, Catholic schoolboys and Hebrew Israelites seemed to capture the worst of America at a moment of extreme political polarization.